The present invention relates to an engagement mechanism for a developing means in an electrostatic copying machine.
The electrostatic copying machine is, in a typical configuration, provided with a rotary drum which rotates once every copying operation at the center portion of the machine body in addition to an electrostatic charger, an exposure member, a developing means, a transfer charger, a separation charger and a cleaner are arranged successively in a peripheral of the rotary drum. Among the constituent elements the rotary drum and the developing means include some consumables having a certain life time which necessitate successive replacements in order to maintain a constant copying quality.
In the past, in order to meet with such requirements there were such copying machines, of which,
(1) one is comprising upper and lower two sections, wherein one side of the upper section being pivotally supported while other side of the upper section being detached from the lower section, thus the constituent elements mentioned above can be removed by dividing a conveying section for a copying paper, and
(2) another is comprising the rotary drum, developing means and cleaner which can be drawn out together in one unit from the machine body.
The former has an advantage of removing the constituent elements comparatively easily, since they can be removed by pivotally supporting one side of the upper section of the machine body while detaching the other side from the lower section and dividing the conveying section of the copying paper. It involves, however, considerably complicated works to ensure an accurate position between the rotary drum and the developing means. Particularly in the large electrostatic copying machine, it requires much trouble for pivotally supporting one side of the upper section while detaching the other side from the lower section and dividing the conveying section of the copying paper, resulting in a difficulty in replacing each constituent element. On the other hand the latter is free from a any disadvantages accompanied in the works for pivotally supporting one side of the upper section while detaching the other side from the lower section and dividing the conveying section of the copying paper, accordingly it is applicable to the large electrostatic copying machine.
With respect to the latter electrostatic copying machine the applicant of the present patent has filed a patent application already [refer to Japanese Patent Publication (unexamined) No. 181058/1983], of which configurations are shown in FIG. 21 and FIG. 22.
In other words, the supporting frame body (5') having the rotary drum (41') and the developing means (43') being removably mounted thereto is provided in such a manner that it may be drawn out through the opening (55') formed at the fixed center portion of the vertical front plate (18') of the copying machine body (1'). The rotary drum (41') and the developing means (43') are mounted between a pair of supporting walls (51') (52') which are mutually connected with the horizontal members (53') (53') and construct the supporting frame body (5') as described in detail in the followings.
The rotary drum (41') is provided with the discs (423) at the openings on both ends of a cylindrical body (422) having a photoreceptor layer (400') on an outer surface, a boss (not illustrated) extending outwardly from the disc (423) and a bearing member (415') to be arranged on the boss, whereby a positioning of the rotary drum (41') may be accomplished by setting the bearing member (415') on a receiving member (501') fixed on said supporting wall (51'). The developing means (43') includes a plate member (424) at the front and rear sides which is provided with a protruded portion (425) having a horizontal bottom contact edge (426) contacting the supporting member (415') at the end on the side of the rotary drum (41') together with a vertical contact edge (419') contacting a vertical contact surface (507') of the receiving member (501') at the edge (427) located beneath the protruded portion (425), whereby the relative position of the rotary drum (41') and the developing means (43') may be controlled by the bottom contact edge (426) and the contact edge (419').
A protrusion receiving part (522) is formed on the mounting body (520) positioned adjustably to the rotary drum (41') by a long hole (521) and a screw (not illustrated) against the supporting wall (51') and an accurate positioning against rotary drum (41') is performed by the contact bottom edge (426) and the contact edge (419') in a mating state between a mounting protrusion (421') protruded at the fixed position of said plate member (424) and the protrusion receiving part (522), whereby the accurate mounting of the developing means (43') may be accomplished by fixing the mounting body (520) by tightening the screw (not illustrated).
Accordingly, the developing means (43') may be set accurately by contacting the bottom contact edge (426) to the bearing member (415') of the rotary drum (41'), moving the developing means (43') so as to cause a contact between the contact edge (419') and the contact surface (507') in the mating state between the mounting protrusion (421') and the protrusion receiving part (522) and fixing the mounting body (520) by the screw (not illustrated).
After being set accurately, it has an advantage of simple removing work of the developing means (43') by lifting it upward to as to detach the mounting protrusion (421') from the protrusion receiving part (522) whenever an exchange of developing agent or a replacement of rotary drum is required.
It requires a certain amount of works, however, to fix the mounting body (520) by the screw (not illustrated) which causes an operational problem of preventing the incorrect positioning of the developing means (43') during such works, further when mounting the developing means (43') it may be required to approach the developing means (43') to the rotary drum (41') by confirming the relative positions of bearing member (415') vs. bottom contact edge (426), receiving member (501') vs. contact edge (419') and protrusion receiving part (522) vs. mounting protrusion (421') respectively with an eye measurement, whereby a problem of unexpected accident may occur such as an undesirable negative effect which causes a scratch on the photoreceptor layer (400') on the rotary drum (41') by the edge of the developing means (43'), e.g. the protrusion (425) etc.
Moreover, since the engagement of the developing means (43') is performed while the supporting frame body (5') being drawn out, it may happen that the supporting frame body (5') will be replaced carelessly with the developing means (43') being removed, accordingly if a copying is performed as it is a copied image may be not formed on the copying paper, that is, a problem of mis-copying will occur.
It is an object of the present invention to improve a performance by dispensing with the job of tightening the screw and prevention of incorrect positioning of the developing means resulted therefrom.
Still another object of this invention is to control the setting of the developing means to a certain direction in order to secure the uniformity of works.
Even still another object of the present invention is to surely preclude the mis-operation from setting the rotary drum with undue force on the main body of the copying machine in a state when the developing means is failed being set.
It is another object of the present invention to prevent an unexpected accident by exactly controlling the direction for mounting the developing means in a constant direction.
It is an additional object of the present invention to surely prevent a breakage-accident of the machine resulting from forcedly setting the rotary drum to the copying machine body in a state in which the developing means was failed to be incorporated.
It is a still further object of the present invention to simplify the engagement operation of the developing means in a state of the machine wherein the supporting frame body was drawn out.
The present invention relates to an electrostatic copying machine wherein the original image is guided onto the photoreceptor body arranged on the rotary drum via the focusing device, forming the electrostatic latent image on the photoreceptor, which is positively changed into the toner image by the developing means and said copying machine is provided with the supporting frame body which can be drawn out from the vertical front plate of the copying machine body and the supporting member and the engagement member separately arranged thereon, said supporting member supporting the rotary drum in a freely rotatable fashion and being provided with the contact surface for controlling the horizontal position of the developing means and the guide for controlling the vertical position thereof, said engagement member being rotatable in one direction from the standard position and being mounted movably with an impetus toward the rotary drum, further the developing means being arranged movably to the rotary drum by engaging the engagement part formed at the fixed position on the developing means to the engagement part provided at the fixed position on said engagement member.